This invention relates generally to fluid delivery devices, and more particularly, has reference to a new and improved device for infusing a drug into an ambulatory patient.
In various clinical situations, the indicated procedure for treating the patient is to administer drugs or other pharmaceutical fluids into his body in a sustained manner over a substantial period of time. Fluids administered in this manner include liquid nutrients, blood, plasma, insulin and hormones.
A simple method for treating the patient in the above manner is to give him repeated bolus injections at various times. That procedure subjects the patient to discomfort and anxiety and also exposes him to the risk of undesirable side effects due to wide fluctuations in the amount of drug in his body at any one time. Furthermore, it demands either the time-consuming process of sterilizing reusable syringes after each injection or the expensive process of using a plurality of disposable syringes. It is also inconvenient for ambulatory patients who return to the physician's office each time an injection is needed.
The intravenous administration set, which includes the familiar bottle suspended above the patient, was developed to overcome some of the problems associated with bolus injections. Unfortunately, the IV set restricts mobility to the extent that it is not well-suited for use with an ambulatory patient.
Other methods for the gradual administration of drugs have been devised to eliminate the need for suspending the drug above the patient and thereby provide him with greater mobility. Mechanical pump dispensers use various types of mechanical pumps to expel the drug from a reservoir. Charged reservoir dispensers store a drug under pressure in a flexible reservoir and then selectively expel that drug by the force of an internal reservoir pressure, the rate of release often being regulated by various valves. Pressurized gas dispensers use a pressurized gas to expel the drug. Osmotic dispensers rely on a solute that exhibits an osmotic pressure gradient against water to dispense the drug.
While the aforedescribed fluid administration techniques have served their purpose, there remains a continuing desire for further improvement therein.
The development of the fluid delivery micropump, described in commonly assigned, co-pending application Ser. No. 016,019, filed by Henri J. R. Maget and Paul Krejci and entitled "Fluid Delivery Micropump", was a major step forward. It overcomes many of the problems associated with the existing devices by providing a self-powered prime mover module which is compact, economical, simple in structure and easy to operate, and which is useful in a micropump capable of delivering a constant flow of fluid at relatively low rates. The pump is sufficiently small and lightweight to be worn by an ambulatory patient and its simple structure makes it easy to use and operate.
Briefly, the prime mover module includes a housing, an electrolytic membrane disposed in the housing and having first and second membrane surfaces, a first material-pervious electrode disposed on the first membrane surface and a second material-pervious electrode disposed on the second membrane surface, an electrical power source, preferably a zinc-air battery, disposed in the housing for establishing a voltage gradient across the electrolytic membrane when exposed to the atmosphere, one or more ports in the housing to establish communication between the battery and the atmosphere, the voltage gradient across the membrane ionizing oxygen at the first material-pervious electrode, transporting the ions through the electrolytic membrane to the second-material pervious electrode, and reconverting the ions to molecules of oxygen which are evolved at the second-material pervious electrode. Removable sealing means close the ports to inactivate the battery. A more detailed description of the structure and function of the device is contained in the referenced patent application, the entire disclosure of which is incorporated herein by reference.
The fluid delivery micropump has many advantages and is particularly well suited for use in satisfying the continual desire for new and improved ambulatory drug delivery devices which are less bulky and conspicuous, more comfortable to wear and more economical. A further need exists for improvements in ambulatory drug delivery devices to make it easier to determine the amount of drug contained in the device and the amount of drug infused into the patient, to make it easier to determine whether the device is operating properly, to enhance user comfort, to promote filtration capabilities and to facilitate proper operation. The present invention fulfulls all of these needs.